Recovery of styrene



July 4 1944-i M. c. K. JONES ETAL l 2,353,040

RECOVERY OF STYRENE Filed Feb. 27, 1941 Vlwunataro 2111.011.' man; del, saLpTlo/Y- inthe solution forni.A

fembodiment of the. same.

Patented d4, 1944v 2.353.040 alloovnnror s'rraENE Miner c. K. Joneeveeioels, and Ala-ea a well, Roselle Park, N. lfassignors, by mesne assignments. to Jacco,

Incorporated, a corporation of Louisiana J Application February 27,1941, serial No. saam s calm. (ol. asc-scsi' The relatively low boiling fraction and thev The. present invention is concerned with the recovery oi styrene. The invention is more particularly concerned with a novel sequence and arrangement of stages by which styrene may be efilciently and economically recovered and segregated from feed streams containing the same utilizing plcric acid. A preferred modication of the process comprises closely fractionating styrene containing feed `mixtures to produce a relatively narrow boiling range fraction, which fraction is subsequently treated under denite conditions with an aqueous solution of plcric acid.

The plcric acid solution is subsequently treated in a manner to segregate and recover the styrene.

It is known in the art that hydrocarbon fractions derived from various sources, such as those derived in the processing of petroleum oils, as

well as hydrocarbon fractions produced in the manufactured gas industry, contain various quantities of styrene. Since styrene comprises an essential and valuable feed material in many processes, such as inthe manufacture of artificial rubber, various processes have been suggested for fr" We have now discovrecovering this material. ered a process by which styrene may be eiciently and economically recovered from hydrocarbon 4 fractions containing the same. Our process com- -prises contacting the'nstyrene containing feed fraction with picric acid either in the solid or Our process may be readily understood by reference to the attached drawing illustrating an The drawing illustrates an adaptation of our .invention for the segregation ofestyrene from hydrocarbon fractions containing the same, utilizing an aqueous solution of -picric acid in the treatment of a segregated relatively narrowly. boiling range feed fracnon. Referring specifically to :the drawing, it is A 4o 20 is cooled in cooling zone 2l, passed to a sepaassumed for the purposes ofillustration that the feed stream comprises a hydrocarbon fraction boiling in the range below about550 F., and is produced in the cracking of petroleum oils. The feed stream is introduced into distillation zone I by means of feed line 2, Before introducing in heating zone 3, to' th= desired temperature.

Temperature and pressure conditions in zone l are adapted to remove overhead by means of .line -4 relatively low boiling hydrocarbon constituents and to remove asabottoms by means of line 5 relatively high boiling .hydrocarbon constituents. An intermediate fraction boiling over a relatively 'narrow boiling range is removed Aas 55 a side stream by means of line 8.

relatively high boiling fraction removed by means of lines l and l respectively may be handled or further refined in any manner desirable. 'The 5 intermediate boiling side stream is cooled in cooling zone 1 and mixed with an aqueous plcric acid solution which is withdrawn from plcric acid solution storage 3 and added by means of line l,

vThe mixture passes through oriflce mixer or equivalent means I0 and is introduced intomltering zone Il by means of line I2. The nltrate is withdrawn from filtering zone H by means of' line I3, .passed to a separator 33 from which unreacted plcric acid is returned by means of line- 39 to plcric acid solution storage 8 and oil by means of line I0 to further handling in any manner desired. The styrene picrate is withdrawn from filtering zone Il by means of line Il as a filter cake, is introduced into crushes l5 and then introduced into an agitation zone I6 in which the crushedstyrene picrate is washed, preferably with hot water which is introduced by means of line l1.

A slurry of styrene picrate is withdrawn from.' agitation zone i6 by means of line I 8 and introduced into distillation zone I9 in which the styrene. is removedm overhead by means of line 20.

Complete removal ofthe styrene from the slurry of styrene picrate in dilute plcric acid solution` troduced by means of line 2|. The dilute plcric acid solution is withdrawn by means of line 22 heated by means of heating zone 23 and intro-,

soils secured'bymeans of open steam, which is in duced into a vacuum evaporator 24. Water is',

a removed overhead fromzone 24 by means of lineI` 25 while conceritratedl picricacid solution is removed by means' of line 28 'htfrecycled to aqueous plcric acid solution storage 8. styrene removed overhead by means of line The fraction comprising styrene is removed by means of uline and passed into fractionating zone 3l. Y.45 Temperature and pressure conditions are adjusted the feed into the distillation zone, it is heated to remove substantial1y"comp1ete1y pure styrene as a side stream by means of line 32, to remove IB-a by means of line 30, and the solid styrene picrate removedv from the respective umts by means of line .31 and handled as described above.

The process widely varied.

of the present invention may be Although the operation has been described with respect to stocks derived in the cracking of petroleum oils, it is to be understood that styrene may be recovered from feed streams derived from any source. For example, the operation is particularly applicable in the recovery of styrene from the light oil which is recovered as a by-product i-n the manufacture of gas. It is also to be understood that the present process may be adapted for the recovery of styrene which is produced from a petroleum oil source by the reaction of ethylene with benzene to form ethyl benzene, which reaction product is subsequently dehydrogenated by a catalytic dehydrogenation operation to produce styrene.

Although solid picric acid may be employed, it is preferred that 1% to 5% solution, preferably aqueous, be utilized. It is also desirable that the solution contact a relatively narrow boiling fraction, as for example, a fraction boiling in the general range from about 280 F. to 310 F., preferably a fraction which boils in the range from about 290 F. to 300 F. When treating a fraction boiling in this range, particularly desirable results are secured providing a 2% aqueous solution of picric acid is employed.

Although the temperatures and pressures may be widely varied depending upon the character of the feed mixtures, the particular picric acid solution, and the like, employed, it has been found that preferred operating temperatures are in the range from about 20 F. to 40 F. Especially desirable temperatures for contacting the picric acid and the styrene containing feed stream are in the range from about 25 F. to about 35 F. In certain operations it may be desirable to employ anti-freezing substances.

When employing a solid picric acid, it is to be understood that any particular size may be employed. The operation may be readily adapted to the use of crystalline picric acid. Such crystals should contain added Water to avoid hazards in handling.

Under certain conditions, when treating a feed stream containing styrene and naphthalene, it may not be desirable to segregate the styrene and naphthalene prior to contacting the same with picric acid. Under these conditions, a mixture of styrene picrate and naphthalene picrate is secured. When employing this operation, the styrene picrate is preferably segregated by heating the mixture of picrate crystals in an aqueous picric acid solution under vacuum. The styrene picrate decomposes, while the naphthalene picrate does not. Upon cooling, the naphthalene picrate recrystallizes and may be removed by filtering.

A mixture of styrene picrate and naphthalene picrate, likewise,may be segregated by dissolving the mixture in benzene with the addition of a small quantity of water, and reacting the same with sodium hydroxide solution to free the styrene and naphthalene to the benzene. The styrene there may be reacted with bromine dissolved in carbon tetrachloride to effect the desired separation.

In order to illustrate the invention further, the following example is given which should not be construed as limiting the same i-n any manner whatsoever.

Example A petroleum feed oil boiling in the range from about 100 F. to 400 F. was distilled and a fraction boiling in the range from about 290 F. to 300 F. segregated. This fraction was contacted with a 2% picric acid solution at 35 F. to form styrene picrate. The styrene picrate was separated by filtration and washed into a still with hot water at a temperature of 175 F. Care was exercised to maintain the temperature below the melting point of the styrene picrate. This slurry of styrene picrate in dilute picric acid solution in the still was steam distilled; substantially 100% pure styrene was then segregated by condensing the same from the overhead vapors. Approximately of the styrene present in the feed oil was recovered by this operation.

What we claim as new and wish to protect by Letters Patent is:

1. Process for the segregation of styrene from petroleum oils containing the same, which comprises contacting said petroleum oils with aqueous picric acid, segregating styrene picrate and recovering the styrene therefrom.

2. Process for the recovery of styrene from petroleum oil feed gases containing the same, which comprises contacting the same with an aqueous solution of picric acid, segregating the styrene picrate and recovering the styrene therefrom.

3. Process for the recovery of styrene from petroleum boiling in the range from about F. to about 400 F., which comprises segregating a fraction boiling in the range from about 280 F. to about 310 F., contacting the same with aqueous picric acid, separating the styrene picrate, and recovering the styrene by distilling the styrene picrate in the presence of steam.

4. Process for the recovery of styrene, which comprises passing impure styrene into contact with an aqueous solution of picric acid, segregating styrene picrate formed thereby, forming a slurry of styrene picrate, subjecting the slurry to distillation to liberate styrene from its combination with picric acid, separating styrene from the distillation product, and returning picric acid ic the contact stage. i

5. Process for the segregation of styrene from a petroleum oil containing the same, which comprises distilling said oil to produce a fraction containing a substantial proportion of styrene, contacting said fraction with an aqueous solution of picric acid, segregating in solid form styrene picrate formed thereby, crushing the styrene picrate, agitating the crushed styrene picrate in the presence of water, distilling the resulting product in the presence of steam, fractionating the styrene-containing distillate obtained thereby to segregate styrene in substantially pure form, concentrating the dilute picric acid solution remaining-from the steam distillation, and returning picric acid to the contacting stage.

MINOR C. K. JONES. ALFRED A. WELLS. 

